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decisive in showing the argument to be fatally ¬‚awed, the argument it-
self taps into a cluster of intuitions that run through deep philosophical
waters. Perhaps for this reason the argument has continued to inspire
individualistic appeals to causal powers, despite acknowledged problems
with Fodor™s original statement of it.17
The basic version of the argument itself is easy to state. Taxonomy or
individuation in the sciences in general satis¬es a generalized version of
individualism about psychology: Sciences taxonomize the entities they
posit or discover by the causal powers that those entities have. Psychology
and the cognitive sciences should be no exception here. But the causal
powers of anything supervene on that thing™s intrinsic, physical prop-
erties. Thus, science taxonomizes entities by properties that supervene
on the intrinsic, physical properties of those entities. Science, and so
psychology, is individualistic.
One way to identify the problem with this argument is to ask what it
is that makes the ¬rst premise about scienti¬c taxonomy in general true.
Given the naturalistic turn supposedly embraced by those working in con-
temporary philosophical psychology, one would think that support here
would come from an examination of actual taxonomic practice across the
sciences. However, once one does turn to look at these practices, it is easy
to ¬nd a variety of sciences that do not taxonomize “by causal powers”:
They instead individuate their kinds relationally, where often historical
relations determine kind membership. Examples often cited here include
species in evolutionary biology, which are individuated phylogenetically
(and so historically), and continents in geology, whose causal powers are
pretty much irrelevant to their individuation as continents.
The problem is particularly acute in the context of this argument for
individualism, since a further premise in the argument states that a thing™s
causal powers supervene on that thing™s intrinsic properties. Thus, one
cannot simply save the ¬rst premise in the argument by stipulating that in-
dividuation in these sciences is “by causal powers,” using some extended
Individualism: Philosophical Foundations 97

or nonstandard sense of that notion. For example, Fodor has acknowl-
edged that scienti¬c taxonomy is often relational, and his attempt to
show how his argument accommodates this fact involves precisely this
sort of broadening of what it means to individuate “by causal powers.” If
one operates with an extended notion of individuation by causal powers,
however, then “causal powers” no longer supervene on an individual™s
intrinsic, physical properties. In adjusting the sense of “causal powers” to
accommodate relational taxonomies in science, we make the other chief
premise in the argument, that causal powers supervene on intrinsic, phys-
ical properties, false. We can take causal powers to be intrinsic properties,
in which case they do supervene on what™s inside an individual, but then
the claim about scienti¬c taxonomy being “by causal powers” is false.
It is for this reason that the argument from causal powers equivocates
on the crucial term “causal powers.” I have argued elsewhere that this
equivocation permeates all versions of the argument. I also think that
we have reason to be skeptical about views of explanation and taxonomy
that place more weight on the distinction between intrinsic and relational
properties than it can bear.18
The cluster of intuitions that persists despite an acknowledgment
that the argument itself is ¬‚awed in something like this way revolve
around the idea that an entity™s causal powers are central to both the place
of that entity in the causal nexus and in how that entity is or should be
taxonomized. To get from this somewhat vague idea to the individualistic
claim that scienti¬c taxonomy is “by causal powers,” one has to establish
some sort of asymmetry between properties that are metaphysically de-
termined by what lies within the boundary of the individual, and those,
like relational properties, that are not. For example, one could claim that
only an entity™s intrinsic properties feature in causal laws governing that
thing™s behavior, or that the causal ef¬cacy that any relational property
has depends only on the intrinsic properties of the entities it relates.
Such views are part of the smallist legacy of corpuscularianism that I
identi¬ed at the end of Chapter 1. The basic problem with them is very
much that with the claim they are invoked to defend: That once one turns
to taxonomic and explanatory practice in a range of sciences, one ¬nds
many examples in which the putative asymmetries “ between causal pow-
ers and other properties, or between intrinsic and relational properties “
do not exist. This is a developed form of the prima facie general prob-
lem that, I claimed in Chapter 1, smallist views in metaphysics and the
philosophy of science face, and we will encounter it again in the next two
chapters in critiquing the standard view of realization.
Individualism and Externalism in Cognitive Sciences
98

Nonetheless, the intuition that individualism does articulate a con-
straint for the explanation of cognition that sciences more generally sat-
isfy, one that would make for a physicalistically respectable psychology,
persists. My view is that this intuition itself seriously underestimates the
diversity in taxonomic and explanatory practice across the sciences, and
that it simply needs to be given up. Attempts to revitalize this sort of
argument for individualism proceed by making the sorts of a priori as-
sumptions about the nature of scienti¬c taxonomies and explanations
that are reminiscent of the generalized, rational reconstructions of scien-
ti¬c practice that governed logical positivist views of science. This should
sound alarm bells for any self-professed naturalist.
There is one difference between individualists and externalists about
psychology emerging from re¬‚ection on the argument from causal pow-
ers worth keeping in mind as we think about the individual in the fragile
sciences more generally. Individualism, especially as it has been articu-
lated by those proposing or defending this particular argument, is touted
as a global thesis about individuation in psychology that follows from an
even more general thesis about individuation in science. Externalism,
especially as defended by those attacking the argument from causal pow-
ers, is accompanied by a more pluralistic view of psychological taxonomy.
This view allows some place for the causal powers of individuals but also
sees scienti¬c (and so psychological) taxonomy in many cases as being
determined by an entity™s relational and even historical properties. These
individuative theses carry with them normative visions about what good
and bad scienti¬c taxonomy, and thus explanation, is like in particu-
lar sciences. In psychology, individualism implies that folk psychology,
together with the vast tracts of psychology proper that incorporate or
develop folk psychology “ including much of social psychology, cogni-
tive developmental psychology, and work on decision making “ involves
a problematic taxonomy of mental states. It also implies that the way to
repair such problematic taxonomies is to modify them to reconcile them
with individualism. Hence, the narrow content program. Externalists are
likely to view scienti¬c taxonomies and scienti¬c explanation as being
sensitive to a range of factors, and to be skeptical about the prospects for
any recipelike prescription regarding proper scienti¬c taxonomy of the
sort that individualists propose.


8 metaphysics and the fragile sciences
What of the more general, putative connection between physicalism and
individualism? If the denial of individualism could be shown to entail
Individualism: Philosophical Foundations 99

the denial of a plausibly general version of physicalism, then externalism
would itself be in real trouble. But like the individualist™s appeal to causal
powers and scienti¬c taxonomy, the move from the general intuitions
that motivate such an argument to the argument itself will likely always
prove problematic. For example, externalists can respect the physical-
istic slogan “no psychological difference without a physical difference”
because the relevant physical differences lie beyond the boundary of the
individual; attempts to re¬ne this slogan (for example, no psychologi-
cal difference without an intrinsic physical difference) are likely either
to beg the question against the externalist, or to invoke a construal of
physicalism that is at least as controversial as individualism itself.
Externalists have not been as attentive to the metaphysical notions
at the core of contemporary materialism as they could have been, how-
ever. When they have so attended they have often opposed prevalent
physicalist or materialist views without offering a substantive, alternative
metaphysics of the mind. Tyler Burge is the most prominent externalist
of whom this could be said. In his original discussion of the implications
of individualism for related views about the mind, Burge claimed that
the rejection of individualism implied the rejection of widely accepted
token-token identity theories of the mind. In much of his later work,
he has also pointed to inadequacies both in arguments from physical-
ist assumptions to individualism and to materialist conceptions of the
metaphysics of mind. At the same time, Burge has emphasized the need
to focus on explanatory practice in order to properly understand meta-
physical issues, such as the nature of mental causation, saying that such
re¬‚ection “motivates less con¬dence in materialist metaphysics than is
common in North American philosophy.”19
The most underdiscussed, relevant metaphysical notion is that of re-
alization. The next two chapters offer an extended treatment of the con-
cept of realization. They will not only prove useful in our current focus
on individualism in psychology, but also in thinking about the role of the
individual in the fragile sciences more generally.
5

Metaphysics, Mind, and Science
Two Views of Realization




1 the metaphysics of mind and the fragile sciences
It is commonplace for materialist philosophers of mind to talk of mental
states as being realized in states of the brain. So much so, that realization
has become part of the very framework in terms of which many conceptu-
alize the metaphysics of mind. However, while the concept of realization
has been invoked in the philosophy of mind and psychology for over forty
years, it has only recently become the subject of direct philosophical theo-
rizing. Implicit in the literature on the metaphysics of mind is the idea that
realization is a general relation, rather than one invoked solely to answer
the mind-body problem. In this chapter, I shall argue that making this
assumption explicit provides reason to rethink the concept of realization.
By the end of this chapter, I hope to have shown how the metaphysical
foundations of the cognitive sciences are intertwined with broader meta-
physical and methodological issues in other parts of the fragile sciences.
Psychologists and cognitive neuroscientists do not, for the most part,
talk of realization, but of the neural correlates, or of the neural mechanisms
for psychological functions and capacities. Cognitive capacities are lo-
calized in states of the brain. It is part of philosophical lore that such
talk is loose-speak for the more metaphysically loaded discussions within
the philosophy of mind cast in terms of supervenience and realization.
This lore is what justi¬es the sense that philosophical discussions of the
metaphysics of mind are continuous with and contribute to the cognitive
sciences, even though one does not hear “realization” in the mouths of
cognitive scientists themselves. It is part of the self-image of naturalistic
philosophy of mind.

100
Metaphysics, Mind, and Science: Two Views 101

Challenging this self-image is no part of my aim in this chapter, though
developing how I think realization should be conceptualized requires
some discussion of the network of concepts to which realization is re-
lated, including those of mechanism and localization within the cognitive
sciences. Having spent the core of the chapter discussing realization in
general, I shall conclude it by returning to neural realization. I begin with
a brief history of how realization came to be so central to the metaphysics
of mind.


2 realization within the philosophy of mind
Contemporary views of realization in the philosophy of mind can be
traced to Hilary Putnam™s use of the notion in the context of his appeal to
Turing machines in discussing the mind-body problem. Putnam argued
that the relationship between mental and physical states should be no
more puzzling (and no more interesting) than the relationship between
the abstract states of a given Turing machine and the structural states
of the device realizing that Turing machine. Putnam drew a distinction
between the logical description of a Turing machine and the physical
states that realize the states to which that description refers, the idea
being that we see mental states as realized by physical states of the brain
in just this sense.
Accompanying this idea were two claims that have had far-reaching
consequences for how philosophers have thought about the mind over
the last forty years: ¬rst, that systems adequately characterized by Turing
machine descriptions can be multiply realized by physical states; and sec-
ond, that there are no signi¬cant barriers to identifying mental states
with brain states. Within a few years, the ¬rst of these ideas, that of the
multiple realizability of mental states, had become a central reason for re-
jecting the second of them, the mind-brain identity thesis, largely through
Putnam™s own in¬‚uence. Thus arose the functionalist view of the mind
that, despite its critics (including a later timeslice of Putnam himself), has
survived as the dominant “ism” in contemporary philosophy of mind.1
With the rise of functionalism, the claim that mental states are realized
in physical states of the brain became part of the received wisdom on the
mind-body relationship. Indeed, the concept of realization, particularly
that of multiple realization, is well-entrenched in the articulation, expla-
nation, and defense of nonreductionist forms of physicalism. Yet perhaps
the most sustained discussion of realization itself, that of Jaegwon Kim,
Individualism and Externalism in Cognitive Sciences
102

advocates reductionism about the mind on the basis of what Kim thinks
is a proper understanding of the metaphysics of realization. The disso-
nance here derives in part from the neglect of the concept of realization
that I mentioned in the opening paragraph, a point that Terence Horgan
observed in a “state of the art” review of the concept of supervenience
for the journal Mind over a decade ago.2
In this respect, at least, the state of the art has changed only very
recently. My read on the current state of the art is that the standard
view of realization, shared by reductionists and nonreductionist alike, is
deeply ¬‚awed, and that there exists a general alternative to that view,
which accords a central place to the idea that realization is essentially
and irreducibly context sensitive.3


3 a sketch of two views of realization
As a way of outlining the chief contrast between these two views of realiza-
tion, I begin with a ¬rst approximation of what I take to be the standard
view of realization as used in the philosophy of mind. While there is a
recognition both of realization as the (two-place) relation that holds be-
tween mental and physical states, and of realizations as the physical states
that occupy the realizer place in this relation, it is the latter of these that
has been the focus of discussion. Intrinsic, physical states of individuals “
more particularly, of the central nervous systems of individuals “ are the
physical realizations of an individual™s mental states, and these realizers
are metaphysically suf¬cient for the presence of the states they realize.
This is what makes realization a metaphysically robust relation simulta-
neously suitable and problematic for underwriting an account of mental
causation: Suitable because metaphysical suf¬ciency would seem to have
the strength to underwrite an account of mental causation; and problem-
atic because, so-construed, physical realizer states, themselves being phys-
ical, seem to leave no room for distinctly mental causation. Thus, while
the intuitions about psychological explanations generated by the Putnam-
Burge thought experiments that we recounted in Chapter 4 may indicate
ways in which our concept of the mental is sensitive to beyond-the-head
factors, such as the nature of the physical environment or facts about one™s
social location, a proper understanding of the metaphysics of realization
points one to an individualistic or internalist view of mental states.
By contrast, the view of realization that I shall propose in this chapter,
and articulate and defend at greater length in the next, takes the context-
sensitive character of mental states to be inherent to their nature, since

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